RE: Help with what I believe is a hardening issue

Gelatine is very sensitive to high temperatures - this will destroy its
"gelling" ability. I kow this from cooking, not science, so I haven't
got a clue why - think it destroys the protein chains (?). So heating up
your gelatine until its really hot is NOT good! It's probably shrinking
up while drying and flaking off the paper, causing the speckles. I use a
water bath of about 50deg C to reliquefy. I also keep unused gelatine
solution in the fridge. You will know if it is really off - it smells
like a dead animal! I use formaldehyde to harden by adding it to the 2nd
gelatine coat. I get it through my University laboratory - they always
have it.

Hope this is of some use
Kate

-----Original Message-----
From: ericawd [mailto:ericawd@memworld.com]
Sent: Thursday, 11 November 2004 1:37 p.m.
To: alt-photo-process-l@sask.usask.ca
Subject: Re: Help with what I believe is a hardening issue

I will admit I may have been a bit lackadaisical at times with the
gelatin. With the last batch I may have let it set out a good while
after initially adding it t the cool water for heating it for the first
coat. So far on the new BFK I have done only the shrinking step and
plan to complete the sizing process tomorrow. I want to try and avoid
whatever
mistake(s) I made on the last batch. To that end I have a few more
questions.

In answer to the suggestions below, I am sure the gelatin was the
correct formula-four .25 ounce packet of gelatin to a liter of water.
The speckling is very much in the non-image areas. Also, I always
develop the prints in water at 75-77 degrees which I arbitrarily picked
because that is what the ground water runs here in Memphis during the
summer months. The most likely suggestion is the spoilage issue.

The first question: Is it possible to get the gelatin too hot when
sizing? I heat it in a microwave to the point that I am unable to put my
finger in for more than a second. There is usually steam coming off the
surface. Could this be related to my speckling problem and related to
developing prints in scalding water?

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